Nonlinear Generation of Fluting Perturbations by Kink Mode in a Twisted Magnetic Tube
We study the excitation of fluting perturbations in a magnetic tube by an initially imposed
kink mode. We use the ideal magnetohydrodynamic (MHD) equations in the cold-plasma
approximation. We also use the thin-tube approximation and scale the dependent and independent variables accordingly. Then we assume that the dimensionless amplitude of the kink
mode is small and use it as an expansion parameter in the regular perturbation method. We
obtain the expression for the tube boundary perturbation in the second-order approximation.
This perturbation is a superposition of sausage and fluting perturbations.